The present invention relates to an internally cooled cable for transmitting high electrical energies, and particularly to a cable comprising an electric conductor surrounding a circumferentially complete channel for conducting a cooling medium, an outer cable jacket surrounding the electric conductor and insulation intermediate the electric conductor and the cable jacket and separating one from the other.
There are already known internally cooled, particularly water cooled, high-energy cables, for instance from the German published patent application No. 1,960,546 or from the publication Draht Coburg 21 (1970) No. 4, entitled "Wassergekuhltes Kabel fur die CERN" (Water-cooled Cable for the CERN), pages 230 to 233. However, the cables disclosed in these publications are not suited for transmission of high electric energies in the region up to 2000 MVA. This can be easily established from considering the selected cable dimensions, such as the diameter of the electric conductor or from the diameter of the cooling channel.
Furthermore, it is known, for instance from the U.S. Pat. No. 3,509,266 to provide a high-voltage cable with a high energy-transmitting capacity, which includes an electric conductor which is sealed and which is provided with an internal channel through which a cooling medium, such as water, is conducted. However, the electric conductor of this cable is not circumferentially complete but rather provided with a fluid-impermeable layer on its outer surface in order to prevent the cooling medium from penetrating into the electric insulation. It is true that this patent discloses that the transmission capacity of a cable can be substantially increased by internally cooling the same; however, no information is provided about the dimensioning of such water-cooled high-voltage cable and particularly about the dimensions of the electric conductor so as to minimize the expenses connected with such a cable, which expenses include the expenses of manufacturing and installing the cable and the operating expenses of the cable.